A Multi-Polarization Reconfigurable Antenna with Isoflux Pattern

With the innovation of space technology, the demand for low earth orbit communication is increasing year by year. Low earth orbit satellites produced in this context are mainly used in remote sensing detection, weather forecasting and data communication fields. Because the earth surface covered by the antenna beam of low earth orbit satellite is spherical, the beam is usually designed as the equal flux form. Because of the problems of polarization mismatch and multipath effect in satellite communication, choosing multipolarization rather than circular polarization as the working state of low earth orbit satellite antenna can better adapt to the complex working environment and ensure the quality of communication. The combination of equal flux beam antenna and multipolarization reconfigurable technology has great application prospects. Based on the design principle of synthesizing linearly polarized waves from a pair of orthogonal circularly polarized waves, a multi-polarization reconfigurable antenna with isoflux beam was proposed in this paper. The antenna consists of a reconfigurable feeding network and a septum polarizer circular waveguide with choke rings. By changing the working states of SP4T switch and SP2T switches embedded in the feeding network, the feeding network will provide different feeding conditions to the circular waveguide, and the antenna can be reconfigured with two kinds of circular polarizations and two kinds of linear polarizations under the action of the septum in the circular waveguide. In addition, the beamforming was realized by introducing choke rings and T-shaped slots structures into the circular waveguide, which ensures that the antenna radiates isoflux pattern under different polarization states. The measured results show that the overlapping impedance bandwidth of −15 dB is 14. 7%, covering 4. 80~5. 56 GHz, and the top of the radiation pattern has a flat effect in the range of θ from −24° to +24°. In the circular polarization states, the spatial axis ratio covers from −51° to +50°, and the coverage range is larger than the flat range at the top of the pattern. The measured results are in good agreement with the simulation results, and the antenna has the advantages of multipolarization and flat top of the pattern, which can meet the needs of multi-polarization application scenarios in mobile communication and satellite communication. © 2024 South China University of Technology. All rights reserved.